spring and fall eagle and osprey surveys for the beech ridge … · 2012. 8. 10. · spring and...

Spring and Fall Eagle and Osprey Surveys

for the Beech Ridge Wind Energy Project,

Greenbrier and Nicholas Counties, West Virginia

March-May and September-October, 2011

Beech Ridge Wind Energy Project 2008 Baltimore Sun photo by John Makely

Prepared for:

Beech Ridge Energy LLC

1 South Wacker Drive, Suite 1900

Chicago, Illinois

Prepared by:

David Young, Zapata Courage, and Lindsey McManus

Western EcoSystems Technology, Inc.

Cheyenne, Wyoming & Waterbury, Vermont

January 23, 2011

NATURAL RESOURCES SCIENTIFIC SOLUTIONS

Beech Ridge Wind Energy Project

Eagle and Osprey Survey Report, Spring and Fall 2011

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EXECUTIVE SUMMARY

Beech Ridge Energy LLC, a wholly-owned subsidiary of Invenergy LLC, has developed the

Beech Ridge Wind Energy Project (BRWEP) in Greenbrier and Nicholas Counties, West

Virginia. The West Virginia Public Service Commission (WV PSC) permit issued for the project

included a requirement for a one-year post-construction study of eagle and osprey use at the

BRWEP. The Technical Advisory Committee for the BRWEP determined that raptor migration

surveys conducted during the migration seasons would fulfill this requirement in part. The

principal objectives of the study were to: (1) provide site-specific osprey, eagle, and other raptor

use data that would be useful in evaluating potential impacts from the Project; and (2) fulfill WV

PSC permit requirements.

Raptor migration surveys were conducted at five survey stations in spring between March 16

and May 13, and in fall between September 7 and October 28, 2011. All surveys were

conducted between the hours of 0900 and 1600 on days conducive to raptor migration. Over

253 surveys, mean use for all raptors, including vultures, was 2.93 birds per observer-hour, and

overall species richness was 1.25 raptor species per survey. Spring mean raptor use, excluding

vultures, was 0.71 birds per observer-hour, while fall raptor use was 0.95 birds per observer-

hour. In spring, vulture use was 2.98 vultures per observer-hour; in fall vulture use was 1.14

vultures per observer-hour. One osprey was observed during spring surveys, and three were

observed during fall surveys. More eagles were observed in spring, with one bald eagle in

spring and none in fall, and six golden eagles in spring and four in fall.

The highest mean raptor and vulture use in spring was at Station 5, with 7.92 birds per

observer-hour, while Station 4 had the highest use in fall, with 2.63 birds per observer-hour.

Daily raptor and vulture use peaked in the middle of the day, during the 1200 hour. Bird use

fluctuated throughout the spring and fall survey periods. In spring, raptor use peaked on April 26

with 15 individuals observed, while vulture use peaked on April 3 with 47 individuals observed.

In fall, raptor use peaked on September 28 with 31 individuals while vultures had two peaks, on

September 9 with 26 individuals and on October 24 with 24 individuals observed.

For raptors observed flying within 800 meters (m) of the survey station, 50.9% were observed

flying in the rotor-swept height (RSH; 41.5 to 118.5 m [136.2 to 388.8 feet] above ground level),

while 42.8% of vultures were observed flying in the RSH. Two of the three ospreys observed

within 800 m were observed within the RSH. One bald eagle and one golden eagle were

observed flying within 800 m of the survey stations, and both were flying in the RSH.

Data collected during spring and fall surveys suggest that the BRWEP receives relatively low

use by ospreys and eagles, which each accounted for approximately or less than one percent of

all raptor use. When averaged over all survey days to provide a comparable metric to other

hawk watch sites, raptor use during the spring and fall study periods was 1.11, and was

substantially lower than average use at four other Hawk Watch sites in the same geographic

region for data from the same survey days (range of 9.15 to 56.85 raptors per observer-hour).



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TABLE OF CONTENTS

EXECUTIVE SUMMARY ............................................................................................................. i

INTRODUCTION ....................................................................................................................... 1

METHODS ................................................................................................................................. 1

Raptor Migration Surveys ....................................................................................................... 1

Survey Stations .................................................................................................................. 1

Survey Methods ................................................................................................................. 3

Observation Schedule ........................................................................................................ 3

Incidental Wildlife Observations ............................................................................................. 3

Statistical Analysis ................................................................................................................. 3

Raptor Diversity and Species Richness .............................................................................. 4

Raptor Use, Percent of Use, and Frequency of Occurrence ............................................... 4

Bird Flight Height ................................................................................................................ 4

Comparison with Other Hawk Watch Sites ......................................................................... 5

RESULTS .................................................................................................................................. 6

Raptor Diversity and Species Richness .................................................................................. 6

Raptor Use, Percent of Use, and Frequency of Occurrence ................................................... 7

Raptors .............................................................................................................................. 7

Vultures .............................................................................................................................. 8

Temporal Use ..................................................................................................................... 9

Seasonal Use ....................................................................................................................10

Flight Height Characteristics .................................................................................................15

Spatial Variation ....................................................................................................................16

Incidental Observations .........................................................................................................22

DISCUSSION............................................................................................................................23

REFERENCES .........................................................................................................................26

LIST OF TABLES

Table 1. Summary of raptor use and species richness during spring and fall raptor migration

surveys at the Beech Ridge Wind Energy Project. .......................................................... 6

Table 2. Total number of groups and individuals for each raptor subtype and species

observed during spring and fall raptor migration surveys at the Beech Ridge Wind

Energy Project. ............................................................................................................... 7

Table 3. Mean use (number of birds per observer-hour), percent of overall use, and

frequency of occurrence for each raptor subtype observed during the spring and fall

raptor migration surveys at the Beech Ridge Wind Energy Project. ................................ 8



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Table 4. Flight height characteristics of raptor subtypes, species, and vultures observed

during the spring and fall raptor migration surveysa at the Beech Ridge Wind Energy

Project. ..........................................................................................................................15

Table 5. Incidental observations of raptors and other wildlife during the spring and fall raptor

migration surveys at the Beech Ridge Wind Energy Project. .........................................22

Table 6. Number of raptors observed per surveyor hour for each survey date at the Beech

Ridge Wind Energy Project and four other established hawk watch sites in the same

geographic region ..........................................................................................................24

LIST OF FIGURES

Figure 1. Overview of the Beech Ridge Wind Energy Project and raptor migration survey

stations. .......................................................................................................................... 2

Figure 2. Mean use (number of birds per observer-hour) by time period (hour) for the spring

and fall raptor migration surveys for all birds, diurnal raptors, and vultures at the

Beech Ridge Wind Energy Project. ................................................................................10

Figure 3a. Total number of individuals observed by survey day for diurnal raptors and

vultures during spring raptor migration surveys at the Beech Ridge Wind Energy

Project. ..........................................................................................................................13

Figure 3b. Total number of individuals observed by survey day for diurnal raptors and

vultures during the fall raptor migration surveys at the Beech Ridge Wind Energy

Project. ..........................................................................................................................14

Figure 4a. Bubble plots of diurnal raptor use (number of raptors per observer-hour) by all

raptor species during the spring raptor migration surveys. .............................................17

Figure 4b. Bubble plots of diurnal raptor use (number of raptors per observer-hour) by all

raptor species during the fall raptor migration surveys. ..................................................18

Figure 4c. Bubble plots of vulture use (number of vultures per observer-hour) during the

spring raptor migration surveys. .....................................................................................19

Figure 4d. Bubble plots of vulture use (number of vultures per observer-hour) during the fall

raptor migration surveys ................................................................................................20

Figure 5. Flight paths of bald eagle, golden eagle, and osprey groups during the spring and

fall raptor migration surveys. ..........................................................................................21



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INTRODUCTION

Beech Ridge Energy LLC (BRE), a wholly-owned subsidiary of Invenergy LLC, has developed a

wind-energy facility, the Beech Ridge Wind Energy Project (BRWEP), in Greenbrier and

Nicholas Counties, West Virginia (Figure 1). BRE contracted Western EcoSystems Technology,

Inc. (WEST) to monitor wildlife resources as part of fulfilling West Virginia Public Service

Commission (WV PSC) permit requirements for the BRWEP.

The WV PSC permit issued for the project included a requirement for a one-year post-

construction eagle and osprey study at the BRWEP. The Technical Advisory Committee for

BRWEP determined that raptor migration surveys conducted during the migration seasons

would fulfill this requirement in part. An additional raptor migration study was completed in the

BRWEP’s proposed expansion area and is described in a separate report. The principal

objectives of the study were to: (1) provide site-specific osprey, eagle, and other raptor use data

that would be useful in evaluating potential impacts from the BRWEP; and (2) fulfill WV PSC

permit requirements. The following report contains results of the 2011 spring and fall surveys,

conducted for ospreys (Pandion haliaetus), eagles, and other raptors.

METHODS

Surveys at the BRWEP during 2011 consisted of raptor migration surveys during the spring and

fall migration seasons, and incidental observations of raptors while field biologists were on site.

Raptor migration surveys were designed to provide visual coverage over large areas and

generally survey for large birds, specifically eagles and ospreys, as well as other raptor species

and vultures.

Raptor Migration Surveys

Survey Stations

Five point-count survey stations were established within the BRWEP to survey for raptors

(Figure 1). Point count stations were established on top of ridges in open, non-forest habitats to

provide good visual coverage in roughly 360 degrees around the station. This maximized

visibility of diurnal migrant raptors over long distances. Each survey plot included an unlimited

distance viewshed centered at the station as with typical raptor migration surveys. The location

of each station was recorded with GPS coordinates and on a hardcopy map.



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Figure 1. Overview of the Beech Ridge Wind Energy Project and raptor migration survey stations.



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Survey Methods

Surveys were conducted according to methods used by the Hawk Migration Association of

North America (HMANA) and Hawk Watch International (HWI) with observers continuously

scanning overhead for migrating raptors. Binoculars were frequently used throughout each

survey period to aid in locating migrating raptors. The date, start and end time of the survey

period, and weather information such as temperature, wind speed, wind direction, barometric

pressure, percent cloud cover, precipitation, and maximum visibility estimates were recorded for

each survey. Weather information was recorded using a Kestrel® 2500 pocket wind meter. Time

of observation, species or best possible identification, number of individuals, age and sex (if

possible), estimation of distance from observer, flight height, and flight direction were recorded

for each raptor observation.

Observation Schedule

During spring migration, each survey station was surveyed approximately three times per week

from March 16 to May 13, 2011. During fall migration, each station was surveyed twice weekly

from September 7 to October 28, 2011. These periods were selected based on information

obtained from regional hawk migration surveys and covered the periods when most migrant

raptors, including eagles and ospreys, were observed at these other hawk watch sites during

spring and fall migrations (HMANA 2011). Survey duration at each station was one hour and

surveys were conducted between approximately 0900 and 1600 hours (hrs), which is the peak

daily period for migrating raptor activity. Surveys were only conducted on days when weather

conditions were conducive to raptor migration (e.g., warm, clear, high pressure conditions).

Incidental Wildlife Observations

The objective of incidental wildlife observations was to record raptors seen outside of

standardized surveys. All raptors observed while the field biologist was on site but not

conducting a standardized survey were recorded in a similar fashion as those observed during a

survey. The observation number, date, time, species, number of individuals, sex/age class,

activity, estimated distance from observer, and height above ground (for flying birds), and

habitat were recorded.

Statistical Analysis

Following field surveys, observers inspected data forms for completeness, accuracy, and

legibility. A Microsoft® ACCESS database was developed to store, organize, and retrieve survey

data. Data were keyed into the electronic database using a pre-defined format to facilitate

subsequent QA/QC and data analysis. A sample of records from the electronic database was

compared to the raw data forms and any errors detected were corrected. Irregular codes or data

suspected as questionable were discussed with the observer and/or project manager. All data

forms, field notebooks, and electronic data files were retained for reference.



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Raptor Diversity and Species Richness

Raptor diversity was represented by the total number of species observed. Species richness

was represented by the mean number of species observed per survey. Species richness for a

visit1 was calculated by averaging the number of species observed across all surveys in that

visit. Species richness for a survey station was calculated by averaging across all visits. Overall

species richness for the season was calculated by averaging across all visits within the season.

Raptor Use, Percent of Use, and Frequency of Occurrence

For raptor migration surveys, observations of birds detected within an unlimited viewshed were

used in the analysis. The common standardized metric for raptor migration surveys is the mean

number of birds per observer-hour. This metric allows comparison between sample locations,

over time (e.g., hours, days, weeks, seasons), or with other studies where similar data exist.

Mean use was calculated by dividing the total number of birds observed during a survey by the

number of hours in the survey. To calculate mean use for any given visit, use was averaged

across all the stations that were surveyed on that date or for that visit. To calculate overall mean

use, the mean use for each visit was averaged for all visits in the season.

To investigate changes in use over time of day, mean use was averaged across all stations for

each time block (e.g., 1000 – 1100 hrs, 1100 – 1200 hrs, etc.). This accounts for variation in

survey effort among stations and visits.

Frequency of occurrence was calculated as the percent of surveys in which a particular species

or raptor type was observed. Percent of use was calculated as the proportion of the overall

mean use that is attributable to a particular species or raptor type. Frequency of occurrence and

percent of use provide relative estimates of species exposure to the wind energy facility. For

example, a species may have high use estimates for the site based on just a few observations

of large groups; however, the frequency of occurrence will indicate that the species occurs

during very few of the surveys and, therefore, may be less likely affected by the facility.

Bird Flight Height

For observations of raptors within 800 meters (m) of the survey station2, the approximate flight

height was recorded at the point where the bird was first observed. This flight height was used

to calculate the percentage of raptors flying within the rotor-swept height (RSH; 41.5 to 118.5 m

[136.2 to 388.8 feet] above ground level) for the BRWEP turbines.

1 A visit is defined as the period or effort required to conduct a complete round of surveys at all five

stations. 2 Due to the difficulty with estimating flight height when there are few reference points, flight height was

not estimated for observations of birds greater than 800 m from the survey station.



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Comparison with Other Hawk Watch Sites

Established hawk watch sites are typically surveyed from one location for a period of time

(hours) each survey day. To calculate daily raptor use for hawk watch sites, the total number of

raptors observed is divided by the total number of observer-hours. To calculate an overall mean

use for the study period at hawk watch sites, the daily mean number of raptors per observer

hour is averaged across all days surveyed.

To generate a metric that would be comparable for the BRWEP study area, daily mean raptor

use was calculated as the average number of raptors per observer hour for all survey stations

visited on that day. To calculate a comparable overall mean use for the study period, this daily

use value was averaged across all days surveyed. Data for the established hawk watch sites

for the same survey days as those at BRWEP were tallied and averaged across all days

surveyed for comparison.



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RESULTS

Raptor migration surveys were conducted at each of the five stations between 26 and 28 times

from March 16 to May 13, and between 23 to 24 times from September 7 to October 28, 2011

(Table 1).

Table 1. Summary of raptor use and species richness during spring and fall raptor migration surveys at the Beech Ridge Wind Energy Project.

Station

Total Number of

Surveys

Total Number of

Species

Mean Use

(number of

birds/hour)

Mean Number of

Species/Survey

Spring

1 26 8 3.78 1.5

2 27 5 1.77 1.04

3 26 6 2.69 1.46

4 28 8 2.78 1.43

5 28 8 7.92 1.54

Total 135 11 3.68 1.34

Fall

1 24 10 2.42 1.33

2 24 6 1.51 1.04

3 23 7 1.72 1.13

4 23 8 2.63 1.35

5 24 8 2.61 0.96

Total 118 12 2.09 1.14

Overall (Spring and Fall)

1 50 11 3.13 1.42

2 51 7 1.64 1.04

3 49 8 2.23 1.31

4 51 9 2.71 1.39

5 52 10 5.47 1.27

Total 253 13 2.93 1.25

Raptor Diversity and Species Richness

A total of 968 raptors and vultures was observed in the BRWEP during the surveys,

representing 13 species and one unidentified accipiter (Table 2), with an overall mean species

richness of 1.25 species per survey for both seasons (Table 1). Turkey vulture (Cathartes aura)

was the most commonly recorded species during the surveys, composing 69.4% of all

observations (Table 2). Excluding vultures, 284 raptors were recorded (Table 2). Four ospreys

were observed, with one in spring and three in fall, accounting for 1.4% of total observed raptors

and 0.4% of all individuals. Ten golden eagles (Aquila chrysaetos) were observed, with six in

spring and four in fall, representing 3.5% of total observed raptors and 1.0% of all individuals.

Only one bald eagle (Haliaeetus leucocephalus) was observed in spring and none in fall.



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Table 2. Total number of groups and individuals for each raptor subtype and species observed during spring and fall raptor migration surveys at the Beech Ridge Wind Energy Project.

Species/Type Scientific Name

Spring Fall Overall Number

of

Groups

Number

of

Individuals

Number

of

Groups

Number

of

Individuals

Number

of

Groups

Number

Of

Individuals

Diurnal Raptors 105 127 111 157 216 284

Accipiters 16 18 17 18 33 36

Cooper's hawk Accipiter cooperii 4 5 4 4 8 9

sharp-shinned hawk Accipiter striatus 12 13 12 13 24 26

unidentified accipiter 0 0 1 1 1 1

Buteos 81 99 80 125 161 224

broad-winged hawk Buteo platypterus 30 37 17 37 47 74

red-shouldered hawk Buteo lineatus 25 30 17 25 42 55

red-tailed hawk Buteo jamaicensis 26 32 46 63 72 95

Northern Harrier 0 0 1 1 1 1

northern harrier Circus cyaneus 0 0 1 1 1 1

Eagles 5 7 4 4 9 11

bald eagle

Haliaeetus

leucocephalus 1 1 0 0 1 1

golden eagle Aquila chrysaetos 4 6 4 4 8 10

Falcons 2 2 6 6 8 8

American kestrel Falco sparverius 2 2 5 5 7 7

merlin Falco columbarius 0 0 1 1 1 1

Osprey 1 1 3 3 4 4

osprey Pandion haliaetus 1 1 3 3 4 4

Vultures 279 506 119 178 398 684

black vulture Coragyps atratus 4 7 2 5 6 12

turkey vulture Cathartes aura 275 499 117 173 392 672

Overall 384 633 230 335 614 968

Raptor Use, Percent of Use, and Frequency of Occurrence

Combined raptor and vulture use was higher in spring (3.68 birds/hour) than fall (2.09; Table 3).

In spring, mean raptor and vulture use varied from 1.77 birds per observer-hour at station 2 to

7.92 birds per observer-hour at station 5 (Table 3). In fall, mean raptor and vulture use ranged

from 1.51 birds per observer-hour at station 2 to 2.63 birds per observer-hour at station 4 (Table

3).

Raptors

Mean raptor use, excluding vultures, was 0.71 birds per observer-hour in spring and 0.95 birds

per observer-hour in fall (Table 3). Buteos had the highest use of all raptor subtypes (0.56 birds

per observer-hour in spring and 0.77 in fall), composing 15.2% of all use in spring and 36.9% of

all use in fall. Buteos were observed during 35.7% of spring surveys and 35.0% of fall surveys.

Broad-winged hawk (Buteo platypterus) was the buteo most commonly observed in spring with



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37 individuals, while red-tailed hawk (B. jamaicensis) was the most commonly observed buteo

in fall with 63 individuals observed (Table 2). Eagles were observed during 3.6% of spring

surveys and 3.2% of fall surveys. Eagle use in spring was 0.04 birds per observer-hour and

eagles represented 1.1% of overall spring raptor and vulture use (Table 3). In fall, eagle use

was 0.02 birds per observer-hour and eagles accounted for 1.2% of overall fall use (Table 3).

Osprey were observed in only 0.7% of spring surveys and osprey use in spring was less than

0.01 ospreys per observer-hour, representing less than 0.1% of overall use (Table 3). Fall

osprey use was 0.01 ospreys per observer-hour, ospreys represented 0.6% of overall use, and

they were observed in 2.4% of all surveys (Table 3).

Vultures

Two vulture species were recorded within the BRWEP, turkey vulture and black vulture

(Coragyps atratus). In spring, vulture use was 2.98 vultures per observer-hour; in fall vulture use

was 1.14 vultures per observer-hour (Table 3). Vultures composed 80.9% of overall use in

spring and were observed in 71.4% of spring surveys (Table 3). In fall, vultures composed

54.4% of overall use, and they were observed in 41.4% of fall surveys (Table 3).

Table 3. Mean use (number of birds per observer-hour), percent of overall use, and frequency of occurrence for each raptor subtype observed during the spring and fall raptor migration surveys at the Beech Ridge Wind Energy Project.

Mean Use Percent of Use Percent Frequency

Species Spring Fall Spring Fall Spring Fall

Overall - All Stations

Diurnal Raptors 0.71 0.95 19.1 45.6 40.7 50.4

Accipiters 0.09 0.10 2.5 4.8 9.3 13.8

Buteos 0.56 0.77 15.2 36.9 35.7 35.0

Northern Harrier 0 0.02 0 1.0 0 4.0

Eagles 0.04 0.02 1.1 1.2 3.6 3.2

Falcons <0.01 0.02 0.2 1.1 1.4 4.0

Osprey <0.01 0.01 <0.1 0.6 0.7 2.4

Vultures 2.98 1.14 80.9 54.4 71.4 41.4

Overall 3.68 2.09 100 100

Station 1

Diurnal Raptors 0.97 1.08 25.6 44.4 53.8 58.3

Accipiters 0.10 0.09 2.7 3.8 15.4 12.5

Buteos 0.79 0.87 20.9 36.0 42.3 45.8

Northern Harrier 0 0.02 0 0.9 0 4.2

Eagles 0.08 0.03 2.0 1.2 7.7 4.2

Falcons 0 0.02 0 0.9 0 4.2

Osprey 0 0.04 0 1.7 0 8.3

Vultures 2.81 1.35 74.4 55.6 73.1 50.0

Overall 3.78 2.42 100 100



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Table 3. Mean use (number of birds per observer-hour), percent of overall use, and frequency of occurrence for each raptor subtype observed during the spring and fall raptor migration surveys at the Beech Ridge Wind Energy Project.

Mean Use Percent of Use Percent Frequency

Species Spring Fall Spring Fall Spring Fall

Station 2

Diurnal Raptors 0.31 1.03 17.3 68.7 25.9 41.7

Accipiters 0 0.04 0 2.9 0 8.3

Buteos 0.29 0.99 16.3 65.7 22.2 41.7

Osprey 0.02 0 1 0 3.7 0

Vultures 1.46 0.47 82.7 31.3 70.4 33.3

Overall 1.77 1.51 100 100

Station 3

Diurnal Raptors 0.86 0.74 31.8 43.0 53.8 52.2

Accipiters 0.14 0.14 5.1 8.1 11.5 17.4

Buteos 0.66 0.53 24.6 30.9 50.0 34.8

Eagles 0.06 0.07 2.1 4.0 3.8 8.7

Vultures 1.83 0.98 68.2 57.0 73.1 43.5

Overall 2.69 1.72 100 100

Station 4

Diurnal Raptors 0.72 1.06 26.0 40.2 42.9 47.8

Accipiters 0.09 0.09 3.4 3.4 10.7 13.0

Buteos 0.54 0.86 19.2 32.7 35.7 39.1

Eagles 0.08 0 2.7 0 7.1 0

Falcons 0.02 0.11 0.6 4.1 3.6 17.4

Vultures 2.06 1.57 74.0 59.8 67.9 47.8

Overall 2.78 2.63 100 100

Station 5

Diurnal Raptors 0.82 0.98 10.3 37.4 35.7 45.8

Accipiters 0.15 0.17 1.9 6.5 10.7 20.8

Buteos 0.64 0.75 8.1 28.9 35.7 20.8

Eagles 0 0.03 0 1.3 0 4.2

Falcons 0.02 0 0.2 0 3.6 0

Osprey 0 0.02 0 0.8 0 4.2

Vultures 7.11 1.63 89.7 62.6 85.7 41.7

Overall 7.92 2.61 100 100

Temporal Use

For mean use throughout the day, raptor use peaked in the 1200-1300 hour block (1.47

birds/observer-hr/survey; Figure 2). Eagles were observed between 1100 and 1600 hrs, with

peak use occurring in the 1400-1500 hour (0.09 birds per observer-hour; Figure 2). Osprey

observations were recorded between hrs 1000 and 1200 with no discernable peak due to so few

observations. Vulture use peaked during the 1200-1300 hr (Figure 2).



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Seasonal Use

Daily raptor activity fluctuated between zero and 15 individuals through the spring study period,

with the peak in activity on April 26 (Figure 3a). Raptors were not observed on four survey days

during the study period (March 16, March 28, April 1, and May 4; Figure 3a). Vulture activity

ranged from zero to 47 individuals per day (Figure 3a). Vulture activity peaked earlier than

raptors, on April 3 (Figure 3a). The days with the fewest vultures observed occurred on March

16 and April 1 with zero individuals, and March 25 with two individuals observed (Figure 3a).

In fall, raptor activity was variable, with peak activity on September 28 with 31 individuals

observed, and zero observed on September 23, October 20-21, and October 27-28 (Figure 3b).

Vulture activity patterns in fall were different than raptors, with observation peaks on September

9 with 26 individuals, and on October 24 with 24 individuals observed. Zero vultures were

observed on 11 different days throughout the fall study period (Figure 3b).

Figure 2. Mean use (number of birds per observer-hour) by time period (hour) for the

spring and fall raptor migration surveys for all birds, diurnal raptors, and vultures at the Beech Ridge Wind Energy Project.



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Figure 2 (continued). Mean use (number of birds per observer-hour) by time period

(hour) for the spring and fall raptor migration surveys for all birds, diurnal

raptors, and vultures at the Beech Ridge Wind Energy Project.



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Figure 2 (continued). Mean use (number of birds per observer-hour) by time period

(hour) for the spring and fall raptor migration surveys for all birds, diurnal

raptors, and vultures at the Beech Ridge Wind Energy Project.



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Figure 3a. Total number of individuals observed by survey day for diurnal raptors and vultures

during spring raptor migration surveys at the Beech Ridge Wind Energy Project.



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Figure 3b. Total number of individuals observed by survey day for diurnal raptors and vultures

during the fall raptor migration surveys at the Beech Ridge Wind Energy Project.



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Flight Height Characteristics

Approximately 51% of raptors observed flying within 800 m of the survey stations were

observed flying in the RSH (Table 4). Two of the three ospreys observed within 800 m were

observed within the RSH. One bald eagle and one golden eagle were observed flying within 800

m of the survey stations, and both were flying in the RSH. For turkey vultures observed within

800 m of the survey station, 42.8% were observed within the RSH (Table 4).

Table 4. Flight height characteristics of raptor subtypes, species, and vultures observed during the spring and fall raptor migration surveys

a at the Beech Ridge Wind Energy Project.

Species/Type

Number

of groups

Number of

individuals

Mean

Flight

Height (m)

Median

Flight

Height (m)

Percent in

Flight

Percent

Within

RSHb

Diurnal Raptors 99 114 40.66 25.0 40.1 50.9

Accipiters 20 21 42.10 35.0 58.3 61.9

Cooper's hawk 5 5 74.00 70.0 55.6 100

sharp-shinned hawk 15 16 31.47 25.0 61.5 50.0

Buteos 66 80 42.20 23.5 35.7 50.0

broad-winged hawk 21 24 38.19 16.0 32.4 37.5

red-shouldered hawk 12 13 44.42 37.5 23.6 69.2

red-tailed hawk 33 43 43.94 25.0 45.3 51.2

Eagles 2 2 52.50 52.5 18.2 100

bald eagle 1 1 25.00 25.0 100 100

golden eagle 1 1 80.00 80.0 10.0 100

Falcons 8 8 15.38 12.0 100 12.5

American kestrel 7 7 15.57 10.0 100 14.3

merlin 1 1 14.00 14.0 100 0

Osprey 3 3 56.67 65.0 75.0 66.7

osprey 3 3 56.67 65.0 75.0 66.7

Vultures 187 271 28.99 20.0 39.6 42.8

black vulture 2 2 47.50 47.5 16.7 50.0

turkey vulture 185 269 28.79 20.0 40.0 42.8

Overall 286 385 33.03 20.0 39.8 45.2 aLimited to observations within 800 m.

bRSH = rotor-swept height of 41.5 to 118.5 m (approximately 136.2 to 388.8 feet) above ground level.



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Spatial Variation

In spring, raptor use by station ranged from 0.31 birds per observer-hour at station 2 to 0.97 at

station 1. In fall, use by station for all raptors ranged from 0.74 birds per observer-hour at station

3 to 1.08 at station 1 (Table 3; Figure 4). In spring, ospreys were observed only at station 2

(0.02 birds per observer-hour), while in fall, ospreys were observed at stations 1 and 5 (Table 3,

Figure 5). In spring, eagles were observed at stations 1 and 4, both with 0.08 eagles per

observer-hour. Eagles were observed during fall surveys at stations 1, 3, and 5 with use ranging

from 0.03 to 0.07 birds per observer-hour (Table 3, Figure 5). Vulture use in spring and fall was

greatest at station 5 (7.11 and 1.63 birds per observer-hour, respectively), while vulture use

recorded at other stations ranged from 1.46 to 2.81 birds per observer-hour in spring and 0.47

to 1.57 in fall (Table 3; Figure 4).



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Figure 4a. Bubble plots of diurnal raptor use (number of raptors per observer-hour) by all raptor species during the

spring raptor migration surveys.



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Figure 4b. Bubble plots of diurnal raptor use (number of raptors per observer-hour) by all raptor species during the fall

raptor migration surveys.



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Figure 4c. Bubble plots of vulture use (number of vultures per observer-hour) during the spring raptor migration

surveys.



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Figure 4d. Bubble plots of vulture use (number of vultures per observer-hour) during the fall raptor migration surveys



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Figure 5. Flight paths of bald eagle, golden eagle, and osprey groups during the spring and fall raptor migration

surveys.



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Incidental Observations

Seven raptor species were recorded as incidental observations, representing 69 individuals

including red-tailed hawk (20 individuals), broad-winged hawk (19 individuals), red-shouldered

hawk (Buteo lineatus; 11 individuals), American kestrel (Falco sparverius; eight individuals),

sharp-shinned hawk (Accipiter striatus; six individuals), Cooper’s hawk (A. cooperii; three

individuals), and barred owl (Strix varia; two individuals; Table 5).

Five mammal species were observed incidentally during the study period including black bear

(Ursus americanus; 10 individuals), white-tailed deer (Odocoileus virginianus; 13 individuals),

coyote (Canis latrans; two individuals), one red fox (Vulpes vulpes), and an unidentified flying

squirrel (Table 5).

Table 5. Incidental observations of raptors and other wildlife during the spring and fall raptor migration surveys at the Beech Ridge Wind Energy Project.

Species Scientific Name Number of

Groups

Number of

Individuals

red-tailed hawk Buteo jamaicensis 19 20

broad-winged hawk Buteo platypterus 16 19

red-shouldered hawk Buteo lineatus 11 11

American kestrel Falco sparverius 8 8

sharp-shinned hawk Accipiter striatus 6 6

Cooper's hawk Accipiter cooperii 3 3

barred owl Strix varia 2 2

Bird Subtotal 7 species 65 69

black bear Ursus americanus 8 10

white-tailed deer Odocoileus virginianus 3 13

coyote Canis latrans 2 2

red fox Vulpes vulpes 1 1

unknown flying squirrel 1 1

Mammal Subtotal 4 species 15 27



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DISCUSSION

In order to fulfill a permit requirement of the WV PSC for the BRWEP, the principal objective of

the study was to provide site-specific osprey and eagle use data during the migration seasons

that would be useful in evaluating potential impacts from the project. In general characteristics

of raptor migration moving through the BRWEP were similar in the spring and fall. Overall

species richness (average number of species per survey) was higher in the spring than fall (1.34

and 1.14, respectively). The total number of all raptors, excluding vultures, was higher in fall

than spring (157 and 127, respectively); however, the total number of all observations, including

vultures, was higher in spring compared to fall (633 and 335, respectively), since many more

turkey vultures were observed in spring. For osprey and eagles, the number of individuals

observed was low and they accounted for approximately or less than 1% of the overall raptor

use recorded. Three ospreys were observed in fall and only one in the spring, and six golden

eagles were observed in spring and four in fall. Only one bald eagle was observed in spring and

none in fall.

In order to compare the relative magnitude of raptor migration moving through the BRWEP, the

number of raptors (vultures excluded) per observer-hour available from the Hawk Migration

Association of North America public website (HMANA 2011) were compiled from sites in the

same region and with the same survey dates as the BRWEP and compared with results from

the BRWEP (Table 6). Belmont Valley Hawk Watch Site, Virginia, is located approximately 113

miles to the west, near Charlottesville, Virginia. Pilot Mountain Hawk Watch Site, North Carolina,

is located approximately 115 miles to the south. Allegheny Front Hawk Watch Site,

Pennsylvania, is located approximately 168 miles north-east of the BRWEP, near Central City,

Pennsylvania, and Washington Monument State Park Hawk Watch Site, Maryland, is located

approximately 185 miles to the north-east, near Boonsboro, Maryland.

The number of raptors per observer-hour at the BRWEP was averaged across the survey dates

to calculate a metric comparable to other established hawk watch sites, and resulted in an

average of 0.91 raptors per observer-hour in the spring and 1.30 raptors per observer-hour in

the fall. These estimates were lower than averages seen at other established regional sites

which ranged from 2.58 to 4.39 raptors per observer-hour in the spring and 9.15 to 56.85

raptors per observer-hour in the fall (Table 6). For most of the survey dates, raptor use within

the BRWEP was usually lower than raptor use recorded at the other Hawk Watch sites on the

same date (Table 6).

In general, results of the studies do not suggest that the magnitude of eagle and osprey

migration through the BRWEP, and the overall raptor migration, is great enough that significant

impacts to these species would be expected.



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Table 6. Number of raptors observed per surveyor hour for each survey date at the Beech Ridge Wind Energy Project and four other established hawk watch sites in the same geographic region.

Date Beech

Ridge, WV Belmont

Valley, VA

Pilot Mountain,

NC

Allegheny Front, PA

Wash. Mon. State Park, MD

Spring

3/16/2011 0 NS 0.17

3/17/2011 1.00 1.29 2.67

3/18/2011 0.79 1.06

3/19/2011 1.40 2.67

3/20/2011 0.60 0.50 7.33

3/25/2011 0.59 4.80 0.00 2.00

3/26/2011 0.60 5.00 1.60 3.27

3/28/2011 0 0.44 0.67

3/29/2011 0.20 0.27 3.00

4/1/2011 0 0.00 3.33

4/3/2011 0.20 0.86 10.53

4/4/2011 1.00 4.40 8.44

4/6/2011 0.20 2.00 0.73 2.50

4/10/2011 2.00 2.11 28.10

4/14/2011 0.60 5.56 5.74

4/15/2011 0.60 25.38 18.40

4/17/2011 0.20 5.40 1.54 5.88

4/21/2011 0.60 1.00 3.33 0.86

4/23/2011 2.00 2.29 0.40

4/25/2011 0.60 6.00 1.86 4.67

4/26/2011 3.00 1.71 2.36 0.73

4/30/2011 2.00 4.59

5/2/2011 2.60 6.73 3.43

5/4/2011 0 2.00 0.00 1.00

5/7/2011 1.80 2.18 0.00 0.86

5/8/2011 0.60 2.00 1.33

5/9/2011 0.80 1.33

5/13/2011 1.40

Average 0.91 2.58 NS 4.39 4.37

Fall

9/7/2011 0.19 0.00

9/8/2011 0.50 4.00

9/9/2011 2.00 0.00

9/10/2011 1.00 2.59 2.22 4.55

9/13/2011 1.00 1.25 6.88 16.78

9/16/2011 0.20 180.84 3.73 269.89 88.40

9/17/2011 0.80 41.33 0.00 71.76 9.92

9/19/2011 0.33 2.40 8.75 4.38 405.41

9/20/2011 1.50 3.14 0.71 13.80 235.82

9/23/2011 0 0.00 0.50 0.00



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Table 6. Number of raptors observed per surveyor hour for each survey date at the Beech Ridge Wind Energy Project and four other established hawk watch sites in the same geographic region.

Date Beech

Ridge, WV Belmont

Valley, VA

Pilot Mountain,

NC

Allegheny Front, PA

Wash. Mon. State Park, MD

9/24/2011 1.60 16.27 4.88 75.26 43.70

9/25/2011 1.60 1.88 51.33 180.47

9/28/2011 6.20 64.50 12.40 162.20

9/30/2011 0.60 5.33 1.57 12.00

10/2/2011 0.80 0.00 4.80

10/4/2011 0.20 2.67 0.00 18.21

10/6/2011 1.60 4.89 13.00 3.80

10/10/2011 2.00 11.60 9.24

10/13/2011 0.40 0.00

10/15/2011 2.80 4.00 12.00

10/16/2011 1.20 5.33 6.00 9.60

10/17/2011 0.80 18.00 5.00 7.31

10/18/2011 4.00 60.24 59.70

10/20/2011 0 0.89 2.48

10/21/2011 0 4.00 0.80 4.24

10/24/2011 3.00 8.50 4.00

10/25/2011 3.50 4.82 8.73

10/27/2011 0 0.00

10/28/2011 0 19.18 4.16

Average 1.30 23.45 9.15 22.33 56.85

Daily count data acquired from HMANA (2011)



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REFERENCES

Hawk Migration Association of North America (HMANA). 2011. Hawk Watch Site Profiles and Hawk

Count Summaries. Homepage available at: http://www.hmana.org/sitesel.php

Hawk Watch International (HWI). Homepage available at: http://www.hawkwatch.org/home/

US Geological Survey (USGS). 2011. The National Map/US Topo. Last updated March 1, 2011.

Homepage available at: http://nationalmap.gov/ustopo/index.html

US Geological Survey (USGS) National Land Cover Database (NLCD). 2001. Land Use/Land Cover

NLCD Data. USGS Headquarters, USGS National Center. Reston, Virginia.

http://www.hmana.org/sitesel.php

http://www.hawkwatch.org/home/

http://nationalmap.gov/ustopo/index.html

spring and fall eagle and osprey surveys for the beech ridge … · 2012. 8. 10. · spring and...

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